Dimension reduction is the major consideration for designing an optical imaging lens in recent years. When reducing the length of the optical imaging lens, however, achieving good optical characteristics becomes a challenging problem.
U.S. Pat. No. 7,502,181, U.S. Pat. No. 7,826,151 and U.S. Pat. No. 8,422,145 all disclosed an optical imaging lens constructed with an optical imaging lens having five lens elements. In these patents, the aperture stop is positioned before the first lens element, and the transition of refracting power of the first two lens elements is positive-negative. However, such configurations still fail to satisfy users needs for a better imaging quality and thinner and slimmer design, because the HFOV (half of field of view) in these patents is merely 32˜33 degrees and the lengths of the optical imaging lenses thereof fall into the range of 6.5˜8.0 mm.
Therefore, there is needed to develop optical imaging lens with a shorter length, while also having good optical characters.